Search

A photoelectron microscope operating with a retarding field analyzer can exploit core level energy shifts in order to image Fermi‐level variations of semiconductor surfaces. Fermi‐level maps of cleaved n‐ and p‐type GaAs (110) resolved to better than 10 μm indicate lateral variations in the surface Fermi level which are often quite abrupt. In agreement with earlier, lower resolution work [J. M. Palau, E. Testemale, and L. Lassabatere, J. Vac. Sci. Technol. 19, 192 (1981)],1 Fermi‐level topography is found to be highly correlated with surface roughness as characterized by scanning electron microscope (SEM), optical microscope, and stylus profilometer. Defective fracture surfaces have two distinct characters within SEM resolution: linear defects (steps and ledges) that may extend over millimeters and smooth glassy areas. Both types of surface defects shift the Fermi level towards midgap. The largest defect derived pinnings encountered to date result in the Fermi level lying 0.5 eV above the valence‐band max...

The optical and mechanical properties of boron nitride vapor deposited at 400 °C are shown to degrade when exposed to synchrotron radiation. The extent of the damage and the rate at which the damage occurs are similar to that first reported by Johnson et al. Transmission through membranes of boron nitride was measured in situ during exposure to x rays. Membranes darkened considerably with the transmission through a typical membrane falling from 50% to 20% after absorbing ∼250 kJ/cm3 of x rays. Changes in local film stress were measured with a simple cantilever technique. Films originally in tension (∼5E8 dyne/cm2) were found to become compressive after absorbing 300 kJ/cm3 of x rays. Both forms of damage responded well to annealing. Fourier transform infrared (FTIR) and near‐edge x‐ray absorption measurements were made to discern the structural differences between degraded and unexposed films. No significant structural changes were observed. Boron nitride films deposited at higher temperatures (600 °C) pr...